1. Field of the Invention
The present invention relates to a navigation device and a method for a route calculation.
2. Description of Related Art
There is a known technique of car navigation devices for performing change and display of routes in view of the remaining energy level of a car. The remaining energy level of a car refers to, for example, the remaining level of fuel such as gasoline in the case of a vehicle which uses an internal combustion engine, the remaining capacity of a battery in the case of an electric vehicle, or the remaining level of hydrogen fuel itself or remaining level of fluid to be converted into hydrogen in the case of a hydrogen vehicle. In addition, “in view of the remaining energy level” refers to a consideration of energy charging at a charging point so as to prevent a lack of energy while the vehicle is traveling. For instance, the route calculation device disclosed in Japanese Laid-Open Patent Publication No. H10-170293 searches a route in which the distance from a departure point to a first energy charge station is equal to or less than the cruising distance and the distance of each energy charge station section from the first energy charge station to a destination point is equal to or less than the cruising distance with the full battery level.